In this paper, we give a classification of non simply connected seven dimensional Reimannian manifolds of constant positive curvature which admit irreducible cohomogeneity-one actions. We characterize the acting groups and describe the orbits. The first and second homo-topy groups of the orbits have been presented as well.

We consider the survivability of planetary systems in the globular cluster 47 Tucanae. We compute the cross sections for the breakup of planetary systems via encounters with single stars and binaries. We also compute the cross sections to leave planets on eccentric orbits. We find that wider planetary systems (d > ∼ 0.3 AU) are likely to be broken up in the central regions of 47 Tucanae (within...

After reviewing the difficulties faced by the conventional theory of planet formation (based upon the aggregation of microscopic dust particles), we describe an alternative hypothesis. We propose that planets form by gravitational collapse at the same time as the star about which they orbit. This concurrent collapse hypothesis avoids theoretical difficulties associated with the conventional mod...

In this paper we determine the tidal distortion parameter km of the secondary partner (mass loser) of the semi-detached eclipsing binary system V621 Cen by comparing the phenomenologically determined orbital period Pb = 3.683549(11) to the Keplerian one P Kep computed with the values of the relevant system’s parameters determined independently of the third Kepler law itself. Our result is km = ...

A planetary body moving on an eccentric orbit around the primary is subject to a periodic perturbing potential, affecting its internal mass distribution. In a previous paper (Rappaport et al., 1997, Icarus 126, 313), we have calculated the periodic modulation of the gravity coefficients of degree 2, for a body on a synchronous orbit. Here, the previous analysis is extended by considering also n...

We have prepared an atomic electron in a three-dimensionally localized wave packet that travels along a highly eccentric orbit between the nucleus and a turning point approximately 1000 Å away. State preparation consisted of two distinct steps. First the electron wave function was localized to the desired orbit by exciting a stationary extreme Stark state from the n 30 manifold of a sodium atom...

We discuss the formation of pulsars with massive companions in eccentric orbits. We demonstrate that the probability for a non-recycled radio pulsar to have a white dwarf as a companion is comparable to that of having an old neutron star as a companion. Special emphasis is given to PSR B1820–11 and PSR B2303+46. Based on population synthesis calculations we argue that PSR B1820–11 and PSR B2303...

The habitable zone for a given star describes the range of circumstellar distances from the star within which a planet could have liquid water on its surface, which depends upon the stellar properties. Here we describe the development of the habitable zone concept, its application to our own solar system, and its subsequent application to exoplanetary systems. We further apply this to planets i...

The detection of gravitational waves from extreme mass ratio inspirals (EMRIs) by the future space-based gravitational-wave detectors demands generation accurate enough waveform templates. Since spin smaller secondary body cannot be neglected for and parameter estimation EMRIs, we study its influence on phase EMRIs with a spinning secondary. We focus generic eccentric equatorial orbits around K...

Motivated by the population of observed multi-planet systems with orbital period ratios 1 < P2/P1 2, we study the long-term stability of packed two-planet systems. The Hamiltonian for two massive planets on nearly circular and nearly coplanar orbits near a first-order mean motion resonance can be reduced to a one-degree-of-freedom problem. Using this analytically tractable Hamiltonian, we apply...